Catalysts supported on natural polymers for the production of carbonates from co2

Abstract

The present invention describes a process to prepare catalyst systems based on metal salts, supported on natural polymers and co-catalyzed by organic bases, for the catalytic transformation of carbon dioxide to organic carbonates through cycloaddition reactions to epoxides. The advantages of the presented system can be summarized on the use of raw materials of low cost for the preparation of the catalyst system, minimal environmental risk due to the low toxicity of the materials used, in some cases biodegradable such as the natural polymers, as well as high catalytic efficiency, reaching selectivities up to 100% and in some cases quantitative yields.

1 . A hybrid catalyst, or catalyst system, for the chemical transformation of carbon dioxide to organic cyclic carbonates through cycloaddition reactions to epoxides, which is composed by an inorganic catalyst, an organic catalyst and a support constituted by a natural polymer. 
     
     
         2 . A hybrid catalyst, or catalyst systems, according to  claim 1 , composed by an inorganic catalyst such as a halide (Cl − , Br − , I − ), preferably bromide or iodide of a metal, preferably although not exclusively alkaline (Li, Na, K, Cs). 
     
     
         3 . A hybrid catalyst, or catalyst system, according to  claim 1 , composed by an organic catalyst, such a nitrogen-containing compound, preferably, but not exclusively DBU, triethyl-amine, methyl-Imidazole, diethanol-amine, 4,4-dimethylaminopyridine, Amino guanidine Bicarbonate, 1,1,3,3-tetramethylguanidine, triethanol-amine, 1,4-diazabiciclo[2,2,2]octane. 
     
     
         4 . A hybrid catalyst, or catalyst system, according to  claim 1 , featured because it contains a support which is basically formed by a natural polymer, preferably, but not exclusively chitin, chitosan, carboxymethyl-cellulose, cellulose and starch. 
     
     
         5 . A procedure to prepare a hybrid catalyst, or catalyst system to perform cycloaddition reactions with epoxides, according to  claim 1  featured because it contains the following stages: 1) preparation of a reaction mixture in aqueous media of the metal halide with the support formed by the natural polymer on weight ratio between 10 and 80%, preferably between 20 and 50% at a temperature between 20 and 100° C., preferably between 40 and 80° C., between 2 and 24 h, preferably between 10 and 20 h and then drying under vacuum at a temperature between 20 and 100° C., preferably between 50 and 80° C. for 1 to 10 h, preferably between 2 and 8 h; 2) addition of the organic catalyst in the reaction mixture at a weight ratio between 1 and 90%, preferably between 10 and 50%; 3) addition of an epoxide in the reaction zone; 4) Injection of CO 2  at a pressure between 100 and 1000 Psi, preferably between 200 and 600 Psi at a temperature between 50 and 200° C., preferably between 60 and 150° C. for a period of time between 0.5 and 8 h, preferably between 1 and 5 h. 
     
     
         6 . A process to prepare a hybrid catalyst or catalyst system to perform CO 2  cycloaddition reactions to epoxides, according to  claim 5 , where the epoxide has the following structure: 
       
         
           
           
               
               
           
         
       
       wherein R and R′ could be, although not exclusively, the following groups: hydrogen, phenyl, alkyl, Ar-alkyl, carboxyl, halogen, vinyl, cycloalkyl, cycloalkylene, nitro, epoxy, amine, alkoxide, amide, siliciure, tiol, nitrile, imidazolil, tiofenil, furanil, piridil, heterociclyl. 
     
     
         7 . A process to prepare a hybrid catalyst, or catalyst system to perform CO 2 -cycloaddition reactions to epoxides, according to  claim 5 , where the carbonate product has the following structure: 
       
         
           
           
               
               
           
         
       
       Where R and R′ could be, although not exclusively, the following groups: hydrogen, phenyl, alkyl, Ar-alkyl, carboxyl, halogen, vinyl, cycloalkyl, cycloalkylene, nitro, epoxy, amine, alkoxide, amide, siliciure, tiol, nitrile, imidazolil, tiofenil, furanil, piridil, heterociclyl.